In vitro evaluation of immunity to Coxiella burnetii.

The rickettsial organism, Coxiella burnetii, is readily phagocytized by macrophages maintained in vitro. This phagocytosis does not lead to destruction of the organism but rather to intracellular multiplication within the macrophage. Specific antiserum added to the macrophage culture before or after infection, or reacted directly with C. burnetii organisms, fails to control subsequent intracellular replication. Macrophage cultures can be treated with lymphocyte products so that intracellular multiplication by C. burnetii is resisted. These lymphocyte products can be obtained from the culture supernatants of sensitized lymphocytes and antigens or from culture supernatants of Concanavalin A and normal lymphocytes. The activation activity of the lymphocyte supernatants paralleled their content of MIF.